Mobiluncus is a genus of anaerobic curved rod-shaped bacteria that typically is not found in healthy patients but is found in vaginal secretions of many patients with a clinical diagnosis of bacterial vaginosis, formerly called "nonspecific vaginitis" (hereinafter sometimes referred to simply as "vaginosis" or "bacterial vaginosis"). In some references, Mobiluncus is referred to as "curved rods," "anaerobic vibrios," or "comma-shaped" bacteria found as part of the vaginal flora.
It is not established that Mobiluncus is the sole cause of vaginosis, even in those cases in which Mobiluncus is found in the vagina. Other changes also occur in the vaginal flora present in the vaginosis patient. In contrast to what is found in a woman without vaginosis, the bacterial flora typical of vaginosis contains less lactobacilli and more anaerobic bacteria, of which Mobiluncus is only one.
In addition to Mobiluncus, the faculative bacterium Gardnerella vaginalis characteristically is present in the vagina of the vaginosis patient and has also been discussed as a possible causal agent of vaginosis, either by itself or in conjunction with one or more species of Mobiluncus or other anaerobic genera. Gardnerella vaginalis and other competing flora tend to grow faster in culture than does Mobiluncus, making isolation of Mobiluncus by strictly mechanical techniques difficult and even impossible in some instances. These problems have interfered with attempts to routinely isolate Mobiluncus as part of diagnostic procedures.
Those skilled in the art have not been able to selectively culture Mobiluncus with satisfactory success. As a consequence, E. Hjelm, et al. (1984), "Primary Isolation of Curved Rods from Women With Vaginal Discharge," Scand. J. Nephrol. Urol., Suppl. 86, 113-116, report resorting to a dilution and sampling technique for primary isolation and identification of Mobiluncus.
A selective culture medium has been proposed by E. Holst, et al. (1984), "Anaerobic Curved Rods in Genital Samples of Women," Scand. J. Nephrol. Urol., Suppl., 86, 117-124. The selective medium of Holst, et al. includes Columbia agar containing one microgram/ml tinidazole in combination with either colistin (10 microgram/ml) or nalidixic acid (15 microgram/ml). The instant inventors find this concentration of tinidazole sufficiently high to inhibit some strains of Mobiluncus mulieris. Furthermore, the suppression by this medium of Gardnerella vaginalis reported by Holst, et al. could not be reproduced by the instant inventors. It is not known if differences in the strains of Gardnerella vaginalis used or in reagents or techniques account for the different results, but, in any event, Gardnerella vaginalis remained as an importantly interfering organism. Holst, et al. reported at page 123 of their study that Mobiluncus (identified by Holst, et al. simply as "anaerobic curved rods") was never found in the absence of Gardnerella vaginalis, which was consistent with their past experience. This emphasizes the significance of Gardnerella vaginalis as a pervasive and important interfering organism.
J. L. Thomason, et al. (1984), "A Selective and Differential Agar for an Anaerobic Comma-shaped Bacteria Recovered from Patients Having Motile Rods and Non-specific Vaginosis," Scand. J. Nephrol. Urol., Suppl., 86, 125-128, report the development of an agar on which Mobiluncus grows well, with competing bacteria being either suppressed or rendered visually distinguishable fom the Mobiluncus by use of Gram stain. Thus, Columbia CNA agar was used as the basal medium because it was one of the media tested that supported maximal growth of Mobiluncus and was at the same time inhibitory to gram-negative organisms. Ten microgram/ml colistin and 15 microgram/ml nalidixic acid were included in the agar, Mobiluncus consistently showing resistance to those antibiotics in those concentrations. Fetal calf serum added to the agar further enhanced growth of Mobiluncus colonies, albeit the growth of other, competing gram-positive organisms also remained possible. Instead of inhibiting these competing organisms, Thomason, et al., attempted to render them visually distinctive. This was done by adding rabbit blood to the agar. The large species of Mobiluncus caused beta-hemolysis in the rabbit blood medium. Two species of Mobiluncus exist, M. mulieris and M. curtisii (respectively sometimes referred to as "large" and "small" or "long" and "short" curved rods), and Thomason has privately informed the instant inventors that only M. mulieris caused beta-hemolysis. Garnerella vaginalis also flourished and produced beta-hemolysis. However, Gardnerella vaginalis was visually differentiated from the Mobiluncus by Gram stain.
Various culture media have been reported to be effective for the culturing of Mobiluncus, independent of the question of selective culturing. A. Fox et al. (1984), "Two Curved Rods in Non-Specific Vaginitis," Scand. J. Nephrol. Urol., Suppl., 86, 93-96, report the use of Columbia agar with five percent horse blood and, alternatively, brain heart infusion agar plus hemin, vitamin K.sub.1, five percent horse blood, and 10 mg/l vancomycin. The reported use of vancomycin here is believed to be a confusion in the text. Other media for the effective cultivation of Mobiluncus are cited by E. Hjelm, et al. (1984), "Primary Isolation of Curved Rods from Women with Vaginal Discharge," Scand. J. Nephrol. Urol., Suppl., 86, 113-116; C. Pahlson, et al. (1984), "Numerical Taxonomy of Motile Anaerobic Curved Rods Isolated from Vaginal Discharge," Scand. J. Nephrol. Urol., Suppl., 86, 251-256; M. Sprott, et al. (1984), "Motile Curved Bacilli," Scand. J. Nephrol. Urol., Suppl., 86, 107-111; A. J. Taylor, et al. (1984), "Morphological and Chemical Characteristics of an Aerobic Curved Rod-Shaped Bacteria from the Female Genital Tract," Scand. J. Nephrol. Urol., Suppl., 86, 97-106; M. Sprott, et al. (1983), "Characteristics of Motile Curved Rods in Vaginal Secretions," J. Med. Microbiol., 16, 175-182; C. Pahlson, et al. (1983), "Characterization of Motile Anaerobic Curved Rods Isolated from Women with Lower Genital Tract Infection in Three Different Countries," Eur. J. Sex. Transm. Dis., 73-75; E. Holst, et al. (1982), "Characteristics of Anaerobic Comma-Shaped Bacteria Removed from the Female Genital Tract," Eur. J. Clin. Microbiol., 1, 310-116; and A. Skarin, et al. (1983), "Antimicrobial Susceptibility of Comma-shaped Bacteria Isolation from the Vagina," Scand. J. Infect. Dis., Suppl., 40, 81-84.
The media used in these references most frequently was Columbia agar supplemented in various combinations with blood (horse, sheep, human, or mixtures thereof), serum (fetal calf, horse), vitamin K.sub.1 (menadione), hemin, yeast extract, colistin, and nalidixic acid. Also used were blood agars and other agars containing heart and brain infusion or other substances, such as yeast extract, liver digest, L-cysteine-HCl, sodium formaldehyde sulphoxylate, hemin, vitamin K.sub.1, sodium formate, sodium fumarate, sodium pyruvate, and sodium succinate. E. Holst, et al. (1983), "Anaerobic Comma-shaped Bacteria Recovered from the Human Genital Tract, A Review," Scand. J. Infect. Dis., Suppl. 40, 23-30, provides an overview of various such culture media used.
Those skilled in the art are cognizant, then, of various culture media in which Mobiluncus can be grown with success. However, a selective growth medium has not yet been developed that encourages Mobiluncus but also suppresses the growth of Gardnerella vaginalis to an effective degree.